(3) Proteomic and metabolomic technologies can be used to elucidate the mechanism of regulation of the metabolic phenotype of hepatocellular carcinoma through differences in the enzyme activities of the s‐GGT and GGT‐II isozymes, including their roles in extracellular matrix remodeling, cell adhesion, and signaling. The gene discussed is GGTLC3; the disease is hepatocellular carcinoma.